I can't speak for panarky, but there are two separate issues here:
1. Rocket implementing the docker image format
2. Rocket PR'ing the rocket image format to docker.
It is 100% reasonable and likely a good business move to reject the PR, but the only reason to be mad about (1) is if it benefits the end user in a way that weakens Docker's market share, which it does.
So are you suggesting docker should merge and maintain support for a container spec they weren't involved with which, was created because docker is "fundamentally flawed"?
I'm sure the pull-request author knew that this would do nothing more than cause fuss in the community. Shykes comment seems to me like it was a response to what seems like a hardly legitimate PR and much like a PR stunt.
Docker has 722 contributors on github, I'm sure the community will discuss and decide what to do with this while I watch this battle play out and work with both products.